Merge tag 'u-boot-stm32-20200514' of https://gitlab.denx.de/u-boot/custodians/u-boot-stm

- stm32mp1: migrate MTD and DFU configuration in Kconfig
- stm32mp1: add command stm32prog
- stm32mp1: several board and arch updates
- stm32mp1: activate data cache in SPL and before relocation
- Many improvment for AV96 board and DHCOR SoM
  (add new defconfig, DDR3 coding on DHCOR SoM, split between board and SOM
   Synchronize DDR setttings on DH SoMs, setting for I2C EEPROM)
- clk: stm32mp1: fix CK_MPU calculation
- DT alignment of stm32mp1 device tree with Linux 5.7-rc2